Semiconductor device

ABSTRACT

Disclosed in an embodiment is a semiconductor device comprising: a semiconductor structure comprising a first conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer disposed between the first conductive type semiconductor layer and the second conductive type semiconductor layer; a second electrode electrically connected to the second conductive type semiconductor layer; and a reflective layer disposed under the second electrode, wherein the second conductive type semiconductor layer comprises a first sub-layer and a second sub-layer disposed between the first sub-layer and the active layer and having an aluminum (Al) composition higher than that of the first sub-layer, the reflective layer comes into contact with the lower surface of the second sub-layer, and the second electrode comes into contact with the first sub-layer.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a U.S. National Stage Application under 35 U.S.C. §371 of PCT Application No. PCT/KR2019/003348, filed Mar. 22, 2019, whichclaims priority to Korean Patent Application No. 10-2018-0039195, filedApr. 4, 2018, whose entire disclosures are hereby incorporated byreference.

TECHNICAL FIELD

Embodiments relate to a semiconductor device.

BACKGROUND ART

A semiconductor device including a compound, such as GaN and AlGaN, hasmany advantages, such as wide and adjustable band-gap energy, and thusmay be diversely used for light-emitting devices, light-receivingdevices, various diodes, and the like.

In particular, a light-emitting device, such as a light-emitting diodeor laser diode, using a III-V group or II-VI group compoundsemiconductor material can realize various colors, such as red, green,blue, or ultraviolet light due to the development of thin-film growthtechnology and device materials. Also, the light-emitting device canrealize efficient white light by using a fluorescent material orcombining colors and has the advantages of low power consumption,semi-permanent lifetime, fast response time, safety, and environmentalfriendliness as compared to existing light sources such as fluorescentlamps and incandescent lamps.

Moreover, due to the development of device materials, when alight-receiving device, such as a photodetector or a solar cell, isfabricated using a III-V group or II-VI group compound semiconductormaterial, the light-receiving device generates a photocurrent byabsorbing light in various wavelength regions, and thus it is possibleto use light in various wavelength regions from a gamma-ray region to aradio-wave region. In addition, the light-receiving device has theadvantages of fast response time, safety, environmental friendliness,and ease of adjustment of device materials and thus may be easily usedfor power control or ultra-high frequency circuits or communicationmodules.

Accordingly, the applications of semiconductor devices are beingexpanded to transmission modules of optical communication means,light-emitting diode backlights which replace cold cathode fluorescentlamps (CCFLs) constituting the backlights of liquid crystal display(LCD) devices, white light-emitting diode lighting devices which mayreplace fluorescent lamps or incandescent lamps, vehicle headlights,traffic lights, sensors for sensing gas or fire, and the like. Inaddition, the applications of semiconductor devices may be expanded tohigh-frequency application circuits, other power control devices, andcommunication modules.

In particular, light-emitting devices that emit light in an ultravioletwavelength range can be used for curing, medical, and sterilizationpurposes by curing or sterilizing.

Recently, research on ultraviolet light-emitting devices has beenactively conducted, but there are problems in that the ultravioletlight-emitting devices are still difficult to realize in a vertical formand are peeled off in the process of separating a substrate and oxidizedby moisture such that optical output power is lowered.

SUMMARY

An embodiment is directed to providing a vertical-type semiconductordevice.

An embodiment is also directed to providing a semiconductor device withexcellent light extraction efficiency.

An embodiment is also directed to providing a semiconductor device withan excellent current spreading effect.

Objectives to be solved by the embodiment are not limited to theabove-described objective and will include objectives and effectivenesswhich may be identified by solutions for the objectives and theembodiments described below.

A semiconductor device according to an embodiment includes asemiconductor structure including a first conductive type semiconductorlayer, a second conductive type semiconductor layer, and an active layerdisposed between the first conductive type semiconductor layer and thesecond conductive type semiconductor layer, a first electrodeelectrically connected to the first conductive type semiconductor layer,a second electrode electrically connected to the second conductive typesemiconductor layer, and a reflective layer disposed below the secondelectrode, wherein the second conductive type semiconductor layerincludes a first sub-layer and a second sub-layer that is disposedbetween the first sub-layer and the active layer and has an aluminum(Al) composition higher than an Al composition of the first sub-layer,the reflective layer is in contact with a bottom surface of the secondsub-layer, and the second electrode is in contact with the firstsub-layer.

Each of the first sub-layer and the second sub-layer may includealuminum (Al) and gallium (Ga), and in a system containing Al and Ga,the Al composition of the first sub-layer may be in a range of 30% to50%, and the Al composition of the second sub-layer may be in a range of50% to 80%.

The Al composition of each of the first sub-layer and the secondsub-layer may gradually increase in a direction toward the firstconductive type semiconductor layer from the second electrode.

A ratio of the Al composition of the second sub-layer and the Alcomposition of the first sub-layer may be in a range of 1:0.375 to 1:1.

The semiconductor structure may further include a recess disposed to apartial region of the first conductive type semiconductor layer throughthe second conductive type semiconductor layer and the active layer, thefirst electrode may be disposed in the recess, and the reflective layerand the second electrode may be disposed to surround the recess.

The first sub-layer may be disposed on a portion of the bottom surfaceof the second sub-layer, a side surface of the first sub-layer may be incontact with the bottom surface of the second sub-layer, the secondelectrode may be disposed below the first sub-layer, and the reflectivelayer may be disposed to be in contact with a side surface and a bottomsurface of the second electrode.

A ratio of an area of the first sub-layer and an area of the secondsub-layer may be in a range of 1:1.01 to 1:1.5, a ratio of an area ofthe first electrode and an area of the second electrode may be in arange of 1:3.88 to 1:5.8, and a ratio of an area of the reflective layerand the area of the second electrode may be in a range of 1:2.4 to1:3.6.

The semiconductor device may further include a first insulating layerdisposed below the semiconductor structure and the reflective layer, afirst conductive layer electrically connected to the first electrode, asecond conductive layer disposed above the first conductive layer andelectrically connected to the reflective layer, a second insulatinglayer disposed between the first conductive layer and the secondconductive layer, a bonding layer disposed below the second conductivelayer, and a substrate disposed below the bonding layer.

The reflective layer may extend toward the bottom surface of the secondsub-layer from a bottom surface of the first sub-layer.

The reflective layer may be in contact with a side surface of the firstsub-layer and may surround the first sub-layer.

Advantageous Effects

According to embodiments, a semiconductor device can be implemented as avertical type.

Further, a light-emitting device with excellent light extractionefficiency can be manufactured.

Various advantages and effects of the present invention are not limitedto the above description and can be more easily understood through thedescription of specific exemplary embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a semiconductor device according toone embodiment.

FIG. 2 is an enlarged view of portion K in FIG. 1 .

FIG. 3 is a conceptual diagram illustrating a process in which light isreflected by a reflective layer.

FIG. 4A is a graph illustrating an aluminum (Al) composition of a secondconductive type semiconductor layer.

FIG. 4B is a view illustrating a modified example of FIG. 4A.

FIG. 5 is a plan view of the semiconductor device according to theembodiment.

FIG. 6 is an enlarged view of portion L in FIG. 5 .

FIG. 7 is a plan view of a semiconductor device according to anotherembodiment.

FIG. 8 is a cross-sectional view taken along line AA′ in FIG. 7 .

FIG. 9 is a conceptual diagram of a package of the semiconductor deviceaccording to one embodiment of the present invention.

FIG. 10 is a plan view of the package of the semiconductor deviceaccording to one embodiment of the present invention.

FIGS. 11A to 11L are sequence diagrams for describing a method ofmanufacturing a semiconductor device according to one embodiment.

DETAILED DESCRIPTION

While the present invention is susceptible to various modifications andalternative forms, particular embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Itshould be understood, however, that there is no intent to limit thepresent invention to the particular forms disclosed, but on thecontrary, the present invention is to cover particular modifications,equivalents, and alternatives falling within the spirit and scope of thepresent invention.

It will be understood that, although the terms “first,” “second,” andthe like may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms are only used todistinguish one element from another. For example, a first element couldbe termed a second element, and a second element could similarly betermed a first element without departing from the scope of the presentinvention. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the another element or intervening elements maybe present. In contrast, when an element is referred to as being“directly connected” or “directly coupled” to another element, there areno intervening elements present.

The terms used herein are for the purpose of describing particularexemplary embodiments only and are not intended to be limiting to thepresent invention. As used herein, singular forms are intended toinclude plural forms as well, unless the context clearly indicatesotherwise. In the present application, it will be further understoodthat the terms “comprise,” “comprising,” “include,” and/or “including”,when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components and/orgroups thereof but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, componentsand/or groups thereof.

Unless otherwise defined, all terms used herein including technical orscientific terms have the same meanings as those generally understood byone of ordinary skill in the art. It should be further understood thatterms, such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and are not to be interpreted in anidealized or overly formal sense unless expressly so defined herein.

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. Regardless ofreference numerals, like numbers refer to like elements throughout thedescription of the figures, and the description of the same elementswill be not reiterated.

A light-emitting structure (identical to a semiconductor structure to bedescribed below) according to an embodiment of the present invention mayoutput light in an ultraviolet wavelength range. As an example, thelight-emitting structure may output light in a near-ultravioletwavelength range (UV-A), light in a far-ultraviolet wavelength range(UV-B), or light in a deep ultraviolet wavelength range (UV-C). Thewavelength range may be determined by an aluminum (Al) composition ratioof a light-emitting structure.

As an example, the UV-A may have a peak wavelength in a range of 320 nmto 420 nm, the UV-B may have a peak wavelength in a range of 280 nm to320 nm, and the UV-C may have a peak wavelength in a range of 100 nm to280 nm.

FIG. 1 is a conceptual diagram of a semiconductor device according toone embodiment, FIG. 2 is an enlarged view of portion K in FIG. 1 , andFIG. 3 is a conceptual diagram illustrating a process in which light isreflected by a reflective layer.

First, referring to FIG. 1 , a semiconductor device 10 according to oneembodiment may include a semiconductor structure 120 including a firstconductive type semiconductor layer 124, an active layer 126, and asecond conductive type semiconductor layer 127, a first electrode 142electrically connected to the first conductive type semiconductor layer124, a second electrode 146 electrically connected to the secondconductive type semiconductor layer 127, and a reflective layer 147disposed below the second electrode 146.

First, the semiconductor structure 120 may include the first conductivetype semiconductor layer 124, the active layer 126, and the secondconductive type semiconductor layer 127 and may further include a recess128 that passes through the second conductive type semiconductor layer127 and the active layer 126 and exposes to a partial region of thefirst conductive type semiconductor layer 124.

The first conductive type semiconductor layer 124 may be implementedwith a compound semiconductor including a III-V group element, a II-VIgroup element, or the like and may be doped with a first dopant. Thefirst conductive type semiconductor layer 124 may be made ofsemiconductor materials having a composition formula ofInx1Aly1Ga1-x1-y1N (0≤x1<=1, 0<=y1<=1, and 0<=x1+y1<=1), for example,semiconductor materials selected from among GaN, AlGaN, InGaN, InAlGaN,and the like. In addition, the first dopant may be an n-type dopant suchas silicon (Si), germanium (Ge), tin (Sn), selenium (Se), or tellurium(Te). When the first dopant is an n-type dopant, the first conductivetype semiconductor layer 124 doped with the first dopant may be ann-type semiconductor layer.

The active layer 126 is disposed between the first conductive typesemiconductor layer 124 and the second conductive type semiconductorlayer 127. The active layer 126 is a layer at which electrons (or holes)injected through the first conductive type semiconductor layer 124 andholes (or electrons) injected through the second conductive typesemiconductor layer 127 meet. The active layer 126 may transition to alow energy level due to the recombination of electrons and holes andemit light having an ultraviolet wavelength.

The active layer 126 may have one structure among a single wellstructure, a multi-well structure, a single quantum well structure, amulti-quantum well (MQW) structure, a quantum dot structure, and aquantum wire structure, but the structure of the active layer 126 is notlimited thereto.

For example, the active layer 126 may include a plurality of well layersand a plurality of barrier layers. Each of the well layers and thebarrier layers may have a composition formula of Inx2Aly2Ga1-x2-y2N(0≤x2<=1, 0<y2<=1, and 0<=x2+y2<=1). An Al composition of the well layermay vary according to a wavelength of emitted light.

The second conductive type semiconductor layer 127 may be formed on theactive layer 126 and implemented with a compound semiconductor includinga III-V group element, a II-VI group element, or the like, and thesecond conductive type semiconductor layer 127 may be doped with asecond dopant. The second conductive type semiconductor layer 127 may bemade of semiconductor materials having a composition formula ofInx5Aly2Ga1-x5-y2N (0≤x5<=1, 0<=y2<=1, and 0<=x5+y2<=1) or materialsselected from among AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. Whenthe second dopant is a p-type dopant such as magnesium (Mg), zinc (Zn),calcium (Ca), strontium (Sr), barium (Ba), or the like, the secondconductive type semiconductor layer 127 doped with the second dopant maybe a p-type semiconductor layer.

The second conductive type semiconductor layer 127 may include aplurality of layers, for example, a first sub-layer 127 a and a secondsub-layer 127 b. In addition, an Al composition of the first sub-layer127 a may be lower than an Al composition of the second sub-layer 127 b.Detailed descriptions of the first sub-layer 127 a and the secondsub-layer 127 b will be given below.

An electron blocking layer (not shown) may be disposed between theactive layer 126 and the second conductive type semiconductor layer 127.The electron blocking layer (not shown) may block electrons suppliedfrom the first conductive type semiconductor layer 124 from flowing outto the second conductive type semiconductor layer 127, therebyincreasing the probability that electrons and holes are recombined witheach other in the active layer 126. An energy band gap of the electronblocking layer (not shown) may be greater than an energy band gap of theactive layer 126 and/or the second conductive type semiconductor layer127.

The electron blocking layer (not shown) may be selected fromsemiconductor materials having a composition formula ofInx1Aly1Ga1-x1-y1N (0≤x1<=1, 0<=y1<=1, and 0<=x1+y1<=1), for example,semiconductor materials selected from among AlGaN, InGaN, InAlGaN, andthe like, but the present invention is not limited thereto. In theelectron blocking layer (not shown), a layer having a high Alcomposition and a layer having a low Al composition may be alternatelydisposed.

A plurality of recesses 128 may be formed in the semiconductor device10, and the number of recesses 128 may be adjusted to adjust opticaloutput power of the semiconductor device 10.

The first electrode 142 may be disposed in the recess 128 and may beelectrically connected to the first conductive type semiconductor layer124.

The first electrode 142 may be an ohmic electrode and may include atleast one among indium tin oxide (ITO), indium zinc oxide (IZO), indiumzinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium galliumzinc oxide (IGZO), indium gallium tin oxide (IGTO), aluminum zinc oxide(AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), IZO nitride(IZON), Al—Ga ZnO (AGZO), In—Ga ZnO (IGZO), ZnO, IrOx, RuOx, NiO,RuOx/ITO, Ni/IrOx/Au, Ni/IrOx/Au/ITO, silver (Ag), nickel (Ni), chromium(Cr), titanium (Ti), aluminum (Al), rhodium (Rh), palladium (Pd),iridium (Ir), tin (Sn), indium (In), ruthenium (Ru), magnesium (Mg),zinc (Zn), platinum (Pt), gold (Au), and hafnium (Hf), but the presentinvention is not limited to such materials.

The second electrode 146 may be disposed below the second conductivetype semiconductor layer 127 and electrically connected to the secondconductive type semiconductor layer 127. Specifically, the secondelectrode 146 may be disposed below the first sub-layer 127 a of thesecond conductive type semiconductor layer 127 so that the firstsub-layer 127 a may be disposed between the second sub-layer 127 b andthe second electrode 146.

The second electrode 146 may be an ohmic electrode and may include atleast one among ITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO, GZO, IZON,AGZO, In—Ga ZnO (IGZO), ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au,Ni/IrOx/Au/ITO, ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au,Ni/IrOx/Au/ITO, Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Sn, In, Ru, Mg, Zn, Pt,Au, and Hf, but the present invention is not limited to such materials.

The reflective layer 147 may be disposed below the second electrode 146and may be electrically connected to the second electrode 146. Inaddition, the reflective layer 147 may reflect light, which is emittedtoward the reflective layer 147 from the active layer 122, to an upperportion of the semiconductor structure 120.

The reflective layer 147 may include a material having conductivity anda reflective function and may include, for example, one of Ag and Rh,but the present invention is not limited to such materials. In addition,the reflective layer 147 may include aluminum, but in this case, stepcoverage is relatively low such that only a portion of the secondelectrode 146 may be covered. However, the present invention is notlimited to such a material.

Further, the semiconductor device 10 according to the embodiment mayfurther include a first insulating layer 131 disposed below thesemiconductor structure 120, a second conductive layer 150 disposedbelow the reflective layer 147, a second insulating layer 132 disposedbelow the second conductive layer 150, a first conductive layer 165electrically connected to the first electrode 142, a bonding layer 160disposed below the first conductive layer 165, and a substrate 170disposed below the bonding layer 160.

First, the first insulating layer 131 may be disposed between thesemiconductor structure 120 and the substrate 170 or may be disposedinside the recess 128. Specifically, the first insulating layer 131 mayelectrically insulate the first conductive type semiconductor layer 121exposed by the recess 128, the second conductive type semiconductorlayer 123, and the active layer 122 from each other. In addition, thefirst insulating layer 131 may electrically insulate the first electrode142 from the active layer 122 and the second conductive typesemiconductor layer 123.

In addition, the first insulating layer 131 may be made of a dielectricor an insulator. For example, the first insulating layer 131 may be madeof an oxide and/or a nitride and may optionally include, for example, atleast one selected from the group consisting of SiO2, SixOy, Si3N4,SixNy, SiOxNy, Al2O3, TiO2, AlN, and the like, but the present inventionis not limited to such materials.

In addition, the first insulating layer 131 may be formed as asingle-layer or a multi-layer. The first insulating layer 131 may beformed as the multi-layer, and thus, an interface between adjacentlayers may be formed.

When the first insulating layer 131 is formed as the single-layer, apath, through which external moisture or contaminants may permeate, maybe exposed due to internal defects. On the other hand, when the firstinsulating layer 131 is formed as the multi-layer, internal defects maybe prevented from being exposed to the outside, thereby reducingexternal moisture and contaminants permeating into the semiconductorstructure 120 through the first insulating layer 131. However, thepresent invention is not limited thereto, and when the internal defectsof the first insulating layer 131 exposed to the outside are small, thefirst insulating layer 131 may be formed as the single-layer.

Further, the first insulating layer 131 may be a distributed Braggreflector (DBR) having a multi-layer structure that includes Si oxide ora Ti compound. However, the present invention is not limited to thestructure, and the first insulating layer 131 may have variousreflective structures. Thus, the first insulating layer 131 may improvelight extraction efficiency.

The second conductive layer 150 may be disposed below the reflectivelayer 147 and the first insulating layer 131 to partially cover thereflective layer 147 and the first insulating layer 131. Accordingly, anelectrode pad 166, the second conductive layer 150, the reflective layer147, and the second electrode 146 may provide one electrical channel.

The second conductive layer 150 may be disposed to surround thereflective layer 147 and may be disposed below the reflective layer 147,the second electrode 146, and the first insulating layer 131. The secondconductive layer 150 may include a material having high adhesion withthe first insulating layer 131 and may be made, for example, of at leastone material selected from the group consisting of materials such as Cr,Ti, Ni, and Au, or an alloy thereof, and may be formed of a single-layeror a plurality of layers. However, the present invention is not limitedto such materials and structures.

The second conductive layer 150 may be disposed between the firstinsulating layer 131 and the second insulating layer 132 and may beprotected from permeation of external moisture or contaminants by thefirst insulating layer 131 and the second insulating layer 132. Inaddition, the second conductive layer 150 may be disposed inside thesemiconductor device 10 and may be surrounded by the second insulatinglayer 132 so as not to be exposed at an outermost side surface of thesemiconductor device 10.

The second insulating layer 132 may electrically insulate the secondelectrode 146, the reflective layer 147, and the second conductive layer150 from the first conductive layer 165.

The second insulating layer 132 and the first insulating layer 131 maybe made of the same material and may be made of at least one selectedfrom the group consisting of SiO2, SixOy, Si3N4, SixNy, SiOxNy, Al2O3,TiO2, and AlN. However, the present invention is not limited to suchmaterials, and the second insulating layer 132 may be made of adifferent material from the first insulating layer 131.

Further, according to the embodiment, since the second insulating layer132 is disposed on the first insulating layer 131 between the firstelectrode 142 and the second electrode 146, when defects are generatedin the second insulating layer 132, the first insulating layer 131 maysecondarily prevent permeation of external moisture and/or othercontaminants. As an example, when the first insulating layer 131 and thesecond insulating layer 132 are formed as one layer, cracks, internaldefects, and the like may be easily propagated in a vertical direction.Accordingly, external moisture or contaminants may permeate into thesemiconductor structure 120 through defects exposed to the outside.

Further, the second insulating layer 132 and the first insulating layer131 may be formed integrally so that a boundary between the firstinsulating layer 131 and the second insulating layer 132 may not bepresent.

However, according to the embodiment, since the second insulating layer132 is separately disposed on the first insulating layer 131, thedefects generated in the first insulating layer 131 are difficult topropagate to the second insulating layer 132. Thus, the first insulatinglayer 131 and the second insulating layer 132 may block the propagationof defects occurring at the interface.

The first conductive layer 165 may be disposed below the secondinsulating layer 132 and the first reflective layer 147. The firstconductive layer 165 may pass through the second insulating layer 132 tobe electrically connected to the first electrode 142 and may also beelectrically connected to the substrate 170 therebelow. Accordingly, thefirst conductive layer 165 may have an electrical channel with the firstelectrode 142 and the substrate 170. The first conductive layer 165 maybe made of at least one material selected from the group consisting ofmaterials such as Cr, Ti, Ni, and Au, or an alloy thereof and may beformed of a single-layer or a plurality of layers. In addition, thefirst conductive layer 165 may be entirely disposed within thesemiconductor device 10.

As described above, the electrode pad 166 may pass through the firstinsulating layer 131 to be disposed on the second conductive layer 150and may be electrically connected to the second conductive typesemiconductor layer 123 so as to have an electrical channel with thesecond conductive layer 150, the reflective layer 147, and the secondelectrode 146.

The electrode pad 166 may have a single-layer or multi-layered structureand may include Ti, Ni, Ag, and Au. As an example, the electrode pad 166may have a structure of Ti/Ni/Ti/Ni/Ti/Au.

The bonding layer 160 may include a conductive material. As an example,the bonding layer 160 may include a material selected from the groupconsisting of gold, tin, indium, aluminum, silicon, silver, nickel, andcopper, or an alloy thereof.

The substrate 170 may be disposed below the bonding layer 160 and may bemade of a conductive material. As an example, the substrate 170 mayinclude a metal or a semiconductor material. The substrate 170 mayinclude a metal having high electrical conductivity and/or thermalconductivity. In this case, the substrate 170 may rapidly dischargeheat, which is generated when the semiconductor device 10 operates, tothe outside. In addition, when the substrate 170 is made of a conductivematerial, the first electrode 142 may be supplied with a current fromthe outside through the substrate 170.

A passivation layer 180 may be disposed to surround an outer surface ofthe semiconductor device 10. Specifically, the passivation layer 180 maybe disposed on top surfaces of the semiconductor structure 120, thefirst insulating layer 131, and the electrode pad 166 and may bedisposed to expose a portion of the electrode pad 166. Accordingly, theelectrode pad 166 may be electrically connected to the outside throughwire bonding or the like.

The top surface of the semiconductor structure 120 may be formed in anuneven shape. For example, a top surface of the first conductive typesemiconductor layer 124 may have an uneven structure, and the unevenstructure enables the extraction efficiency of light emitted from thesemiconductor structure 120 to be improved. The uneven structure mayhave different average heights based on an ultraviolet wavelength andmay have various heights based on the peak wavelength of light emittedto the semiconductor structure 120. Accordingly, the light extractionefficiency of the semiconductor device 10 may be improved.

Referring to FIGS. 2 and 3 , as described above, in the secondconductive type semiconductor layer 127, the Al composition of the firstsub-layer 127 a may be lower than the Al composition of the secondsub-layer 127 b. In addition, each of the first sub-layer 127 a and thesecond sub-layer 127 b may be composed of a system containing Al andgallium (Ga). For example, the first sub-layer 127 a and the secondsub-layer 127 b may each include AlGaN and InAlGaN, but the presentinvention is not limited thereto.

Specifically, the Al composition of the second sub-layer 127 b may be ina range of 50% to 80%. In addition, when the Al composition of thesecond sub-layer 127 b is greater than or equal to 50%, the problem ofabsorbing light may be reduced, and when the Al composition of thesecond sub-layer 127 b is less than or equal to 80%, the problem ofdegrading current injection efficiency may be reduced. As an example,when the Al composition of the well layer is 40%, the Al composition ofthe second sub-layer 127 b may be 50%.

The Al composition of the first sub-layer 127 a may be lower than the Alcomposition of the well layer. When the Al composition of the firstsub-layer 127 a is higher than the Al composition of the well layer, thefirst sub-layer 127 a may not be sufficiently ohmic with the secondelectrode 146 due to an increase in resistance therebetween, and currentinjection efficiency may be reduced.

The Al composition of the first sub-layer 127 a may be greater than orequal to 30% and less than or equal to 50%. When the Al composition isless than or equal to 50%, it is possible to lower the resistance withthe second electrode. When the Al composition is greater than or equalto 30%, the problem of absorbing light in the first sub-layer 127 a maybe reduced.

In the semiconductor device according to the embodiment, a ratio of theAl composition of the second sub-layer and the Al composition of thefirst sub-layer may be in a range of 1:0.375 to 1:1. When the Alcomposition ratio is less than 1:0.375, the light absorbed by the firstsub-layer 127 a increases and thus the light extraction may be degraded,and when the Al composition ratio is greater than 1:1, the firstsub-layer 127 a may not be sufficiently ohmic with the second electrodedue to an increase in resistance therebetween and thus electricalcharacteristics may be degraded.

A thickness T2 of the first sub-layer 127 a may be in a range of 1 nm to30 nm. The first sub-layer 127 a may absorb ultraviolet light so thatoptical output power may be improved by controlling the thickness of thefirst sub-layer 127 a to be as thin as possible.

In addition, when the thickness of the first sub-layer 127 a is greaterthan or equal to 1 nm, it is possible to decrease resistance of thefirst sub-layer 127 a and thus improve electrical characteristics of thesemiconductor device. Also, when the thickness is less than or equal to30 nm, it is possible to improve optical output power efficiency bydecreasing the amount of light absorbed by the first sub-layer 127 a.

In addition, a thickness T3 of the second sub-layer 127 b may be greaterthan 10 nm and less than 50 nm. As an example, the thickness of thesecond sub-layer 127 b may be 25 nm. When the thickness of the secondsub-layer 127 b is greater than or equal to 10 nm, it is possible tosecure current-spreading characteristics of the second sub-layer 127 b.In addition, when the thickness is less than or equal to 50 nm, it ispossible to secure injection efficiency for second carriers injectedinto the active layer 126 and lower an absorption rate of light emittedfrom the active layer 126 in the second sub-layer 127 b.

In addition, the thickness T2 of the first sub-layer 127 a may bedifferent from the thickness T3 of the second sub-layer 127 b. As anembodiment, the thickness T2 of the first sub-layer 127 a may be lessthan the thickness T3 of the second sub-layer 127 b. A ratio of thethickness of the first sub-layer 127 a and the thickness of the secondsub-layer 127 b may be in a range of 1:1.5 to 1:20. When the thicknessratio is greater than 1:1.5, the thickness of the second sub-layer 127 bincreases, and thus it is possible to improve current injectionefficiency. In addition, when the thickness ratio is less than 1:20, thethickness of the first sub-layer 127 a increases, and thus the problemof degrading crystallinity may be reduced. When the first sub-layer 127a is too thin, it is necessary to rapidly change the Al composition inthe range of the thickness, and thus the crystallinity may be degraded.

In addition, the Al composition of the first sub-layer 127 a maydecrease in a direction away from the active layer 126. The firstsub-layer 127 a may have a lower Al composition than the well layer inorder to achieve low contact resistance with the second electrode 146.Accordingly, the first sub-layer 127 a may absorb a portion of the lightemitted from the active layer 126 as described above.

In addition, a ratio of the thickness T2 of the first sub-layer 127 aand a total thickness T1 of the second conductive type semiconductorlayer 127 may be 1:3 to 1:70. When the thickness ratio is greater than1:3, the first sub-layer 127 a may secure electrical characteristics(e.g., an operating voltage) of the semiconductor device. When thethickness ratio is less than 1:70, the first sub-layer 127 a may secureoptical characteristics (e.g., optical output power) of thesemiconductor device.

Further, the Al composition of each of the first sub-layer 127 a and thesecond sub-layer 127 b may gradually increase in a direction toward thefirst conductive type semiconductor layer 124 from the second electrode146. Here, the vertical direction refers to a second direction (a y-axisdirection), a first direction (an x-axis direction) is a directionperpendicular to the second direction (the y-axis direction), and athird direction (a z-axis direction) is a direction perpendicular toboth the first direction (the x-axis direction) and the second direction(the y-axis direction). For example, the vertical direction may be thesame as a direction in which each layer is stacked in the semiconductorstructure 120. In addition, the first sub-layer 127 a and the secondsub-layer 127 b may be reduced in width differently. For example, adecreasing rate of aluminum in the first sub-layer 127 a may be lessthan a decreasing rate of aluminum in the second sub-layer 127 b.

Further, the first sub-layer 127 a may be disposed on a portion of abottom surface of the second sub-layer 127 b. A side surface 127 a-1 ofthe first sub-layer 127 a may be in contact with a bottom surface 128b-2 of the second sub-layer 128 b. For example, the first sub-layer 127a may include the side surface 127 a-1 and a bottom surface 127 a-2, andthe second sub-layer 127 b may include the side surface 127 a-1 and thebottom surface 127 a-2.

In this case, the side surface 127 a-1 of the first sub-layer 127 a maybe in contact with the bottom surface 128 b-2 of the second sub-layer127 b, and the bottom surface 127 a-2 of the first sub-layer 127 a maybe in contact with a top surface of the second electrode 146.Accordingly, the second conductive type semiconductor layer 127 may havea step portion through which a portion of the bottom surface of thesecond sub-layer 127 b is exposed. A ratio of an area of the firstsub-layer 127 a and an area of the second sub-layer 127 b may be in arange of 1:1.01 to 1:1.5. When the area ratio is less than 1:1.01, aproblem exists in that a process is difficult and light is absorbed inthe first sub-layer 127 a, and when the area ratio is greater than1:1.5, the area of the second sub-layer 127 b becomes great such thatreliability is degraded due to the step portion between the secondsub-layer 127 b and the first sub-layer 127 a.

Accordingly, since the area of the first sub-layer 127 a and the area ofthe second sub-layer 127 b have the above-described area ratio,electrical characteristics may be improved through low resistancebetween the first sub-layer 127 a and the second electrode 146 whileminimizing the amount of light absorbed by the first sub-layer 127 a.With such a configuration, in the semiconductor device according to theembodiment, electrical characteristics (e.g., an operating voltage) maybe secured and optical output power may be improved.

In addition, the reflective layer 147 may be disposed below the secondconductive type semiconductor layer 127 and the second electrode 146.Specifically, the reflective layer 147 may be disposed to be in contactwith each of the side surface 127 a-1 of the first sub-layer 127 a and abottom surface 127 b-2 of the second sub-layer 127 b. That is, thereflective layer 147 may be disposed along the side surface 127 a-1 ofthe first sub-layer 127 a to have a stepped structure. In addition, thereflective layer 147 may be disposed to extend toward the bottom surface127 b-2 of the second sub-layer 127 b from the side surface 127 a-1 ofthe first sub-layer 127 a. In other words, the reflective layer 147 maybe disposed to overlap the first sub-layer 127 a and the secondsub-layer 127 b in the vertical direction, but, in a partial region, tooverlap only the second sub-layer 127 b in the vertical direction.Further, the reflective layer 147 may partially overlap the firstsub-layer 147 a in the first direction (in the x-axis direction) or inthe third direction (the z-axis direction), and, at the lower side ofthe second electrode 146, the reflective layer 147 may not overlap thefirst sub-layer 147 a in the first direction (in the x-axis direction)or in the third direction (the z-axis direction). Thus, since thereflective layer 147 is in contact with the bottom surface 127 b-2 ofthe second sub-layer 127 b, light generated in the active layer 126 maybe maximally prevented from being absorbed by the first sub-layer 127 a.In addition, even when light L1 is emitted toward the substrate 170through the second sub-layer 127 b, the light L1 may be reflected towardan upper portion of the semiconductor device by the reflective layer 147so that optical characteristics (e.g., light extraction efficiency) maybe improved.

Further, since the reflective layer 147 is disposed to be in contactwith the side surface 127 a-1 of the first sub-layer 127 a, thereflective layer 147 may reflect light L2, which is emitted downwardthrough the side surface 127 a-1 of the first sub-layer 127 a, towardthe upper portion of the semiconductor device.

Accordingly, in the semiconductor device according to the embodiment,the reflective layer 147 is disposed to surround the second electrode146 therebelow and the side surface 127 a-1 of the first sub-layer 127 aand to be in contact with the bottom surface 127 b-2 of the secondsub-layer 127 b, thereby improving both electrical and opticalcharacteristics.

FIG. 4A is a graph illustrating an Al composition of the secondconductive type semiconductor layer, and FIG. 4B is a view illustratinga modified example of FIG. 4A.

In FIGS. 4A and 4B, the Al composition of the second conductive typesemiconductor layer may vary in a direction in which a thickness thereofincreases. The Al composition of the second conductive typesemiconductor layer 127 may decrease toward a bottom surface thereof.

The Al composition of the second conductive type semiconductor layer 127may be maintained from a top surface (a point where the thickness iszero, that is, a top surface of the second sub-layer 127 b) to thebottom surface of the second sub-layer 127 b. In addition, the Alcomposition may be reduced from the top surface of the first sub-layer127 a to the bottom surface of the first sub-layer 127 a. For example,as shown in FIG. 4A, the Al composition of the first sub-layer 127 a maybe linearly reduced, and as shown in FIG. 4B, the Al composition of thefirst sub-layer 127 a may be reduced for each step. For example, the Alcomposition of the first sub-layer 127 a may be varied to have a flatregion f and an inclined region d. The flat region f is a region inwhich the Al composition is maintained, and the inclined region d is aregion in which the Al composition increases or decreases.

FIG. 5 is a plan view of the semiconductor device according to theembodiment, and FIG. 6 is an enlarged view of portion L in FIG. 5 .

Referring to FIGS. 5 and 6 , the semiconductor device may include aplurality of first regions 136 separated according to the firstelectrode 142 in a plan view. The plurality of first regions 136 may bedisposed to be spaced apart from each other and may have various shapes.As an example, the first region 136 may have a polygonal shape, such asa hexagonal, octagonal, or triangular shape, or a circular shape.

In addition, the reflective layer 147 may be disposed in the firstregion 136 and, specifically, may be disposed to surround the recess 128and the first electrode 142 in a plan view (an XZ plane). Accordingly, acurrent may be injected through the first electrode 142, and the firstelectrode 142 and the reflective layer 147 may be disposed in a regionhaving a current density of 30% to 40% based on 100% of a currentdensity of the first electrode 142 so that light generated in a regionaround the first electrode 142 may be reflected upward.

For example, the reflective layer 147 may be disposed to surround thefirst electrode 142 to reflect the light emitted downward through thesecond sub-layer toward the upper portion of the semiconductor device,thereby improving light extraction efficiency.

In addition, in the semiconductor device, a ratio of an area 51 of thefirst electrode 142 and an area S2 of the second electrode 146 may be ina range of 1:3.88 to 1:5.8. When the area ratio is less than 1:3.88, anarea for ohmic contact is reduced as the area of the second electrodedecreases, and thus there is a problem of increasing resistance. Inaddition, when the area ratio is greater than 1:5.8, light is absorbedby the second sub-layer in ohmic contact with the second electrode, andthus there is a problem of degrading light extraction.

In addition, in the semiconductor device, a ratio of an area S3 of thereflective layer 147 and the area S2 of the second electrode 146 may bein a range of 1:2.4 to 1:3.6. When the area ratio is less than 1:2.4,light is absorbed by the second electrode 146 and the first sub-layer,and thus there is a problem of degrading light extraction efficiency.When the area ratio is greater than 1:3.6, there is a problem in that anarea of the ohmic contact through the second electrode 146 is reduced.

In addition, a minimum width W1 of the second electrode 146 may be lessthan a minimum width W3 of the reflective layer 147. In addition, aratio of the minimum width W1 of the second electrode 146 and theminimum width W3 of the reflective layer 147 may be in a range of 1:2.5to 1:3.5. When the width ratio is less than 1:2.5, the reflective layer147 may not surround the second electrode 146 and the first sub-layer127 a, and thus there is a problem in that light extraction efficiencyis degraded due to the light reflection. When the width ratio is greaterthan 1:3.5, the area of the ohmic contact may be reduced, and thus thereis a problem in that electrical characteristics are degraded.

In addition, the minimum width W3 of the reflective layer 147 may bedifferent from a minimum width of the first sub-layer 127 a. As anembodiment, the minimum width W3 of the reflective layer 147 may begreater than the minimum width of the first sub-layer 127 a. Inaddition, the minimum width of the first sub-layer 127 a may be greaterthan or equal to the minimum width of the second electrode 146.

Further, a ratio of the minimum width W1 of the second electrode 146 anda distance W2 between the adjacent recesses may be in a range of 1:3 to1:10. When the length ratio is less than 1:3, the area of the activelayer is reduced compared to the increased area of the recess 128, andthus there is a limit in that light extraction efficiency is degraded.When the length ratio is greater than 1:10, current spreading throughthe first electrode 142 of the recess may be reduced, and thus opticalcharacteristics may be deteriorated.

FIG. 7 is a plan view of a semiconductor device according to anotherembodiment, and FIG. 8 is a cross-sectional view taken along line AA′ inFIG. 7 .

Referring to FIGS. 7 and 8 , a semiconductor device 10′ according toanother embodiment may include a semiconductor structure 120 including afirst conductive type semiconductor layer 124, an active layer 126, anda second conductive type semiconductor layer 127, a first electrode 142electrically connected to the first conductive type semiconductor layer124, and a second electrode 146 electrically connected to the secondconductive type semiconductor layer 127.

As described above, the semiconductor structure 120 may include thefirst conductive type semiconductor layer 124, the active layer 126, andthe second conductive type semiconductor layer 127 and may include arecess 128 that passes through the second conductive type semiconductorlayer 127 and the active layer 126 and exposes a partial region of thefirst conductive type semiconductor layer 124. In addition, the contentsof the first electrode 142, the second electrode 146, and thepassivation layer 180 may also be equally applied.

Further, as described above, the second conductive type semiconductorlayer 127 may include a first sub-layer 127 a and a second sub-layer 127b, and the second sub-layer 127 b may be disposed between the firstsub-layer 127 a and the active layer 126.

In addition, the second electrode 146 may be disposed on the firstsub-layer 127 a, and a reflective layer 147 may be disposed to surrounda side surface of the first sub-layer 127 a so that light extractedthrough the second sub-layer 127 b may be reflected toward the sidesurface of the first sub-layer 127 a or a lower portion of thesemiconductor device.

As in the aforementioned description, an Al composition of the firstsub-layer 127 a may be less than an Al composition of the secondsub-layer 127 b. In addition, the Al composition of the second sub-layer127 b may be in a range of 50% to 80%. In addition, when the Alcomposition of the second sub-layer 127 b is greater than or equal to50%, the problem of absorbing light may be reduced, and when the Alcomposition of the second sub-layer 127 b is less than or equal to 80%,the problem of degrading current injection efficiency may be reduced. Asan example, when an Al composition of a well layer is 40%, the Alcomposition of the second sub-layer 127 b may be 50%.

The Al composition of the first sub-layer 127 a may be lower than the Alcomposition of the well layer. When the Al composition of the firstsub-layer 127 a is higher than the Al composition of the well layer, thefirst sub-layer 127 a may not be sufficiently ohmic with the secondelectrode 146 due to an increase in resistance therebetween, and currentinjection efficiency may be reduced.

In addition, each of the first sub-layer 127 a and the second sub-layer127 b may be composed of a system containing Al and Ga. For example, thefirst sub-layer 127 a and the second sub-layer 127 b may each includeAlGaN and InAlGaN, but the present invention is not limited thereto. TheAl composition of the first sub-layer 127 a may be greater than or equalto 30% and less than or equal to 50%. When the Al composition is lessthan or equal to 50%, it is possible to lower the resistance with thesecond electrode. When the Al composition is greater than or equal to30%, the problem of absorbing light in the first sub-layer 127 a may bereduced.

In addition, a thickness of the first sub-layer 127 a may be less than athickness of the second sub-layer 127 b. A ratio of the thickness of thefirst sub-layer 127 a and the thickness of the second sub-layer 127 bmay be in a range of 1:1.5 to 1:20. When the thickness ratio is greaterthan 1:1.5, the thickness of the second sub-layer 127 b increases, andthus it is possible to improve current injection efficiency. Also, whenthe thickness ratio is less than 1:20, the thickness of the firstsub-layer 127 a increases, and thus the problem of degradingcrystallinity may be reduced. When the first sub-layer 127 a is toothin, it is necessary to rapidly change the Al composition in the rangeof the thickness, and thus the crystallinity may be degraded.

FIG. 9 is a conceptual diagram of a package of the semiconductor deviceaccording to one embodiment of the present invention, and FIG. 10 is aplan view of the package of the semiconductor device according to oneembodiment of the present invention.

Referring to FIG. 9 , a package of the semiconductor device 10 mayinclude a body 2 including a groove 3 (opening), the semiconductordevice 10 disposed in the body 2, and a pair of lead frames 5 a and 5 bdisposed in the body 2 and electrically connected to the semiconductordevice 10. The semiconductor device 10 may include all of theabove-described components.

The body 2 may include a material or a coating layer that reflectsultraviolet light. The body 2 may be formed by stacking a plurality oflayers 2 a, 2 b, 2 c, 2 d, and 2 e. The plurality of layers 2 a, 2 b, 2c, 2 d, and 2 e may include the same material or different materials. Asan example, the plurality of layers 2 a, 2 b, 2 c, 2 d, and 2 e mayinclude an aluminum material.

The groove 3 may be formed to be wider as a distance from thesemiconductor device 10 is increased, and a step portion 3 a may bepresent on an inclined surface thereof.

A light-transmitting layer 4 may cover the groove 3. Thelight-transmitting layer 4 may be made of a glass material, but thepresent invention is not necessarily limited thereto. A material for thelight-transmitting layer 4 is not specifically limited as long as thematerial is capable of effectively transmitting ultraviolet light. Theinside of the groove 3 may be an empty space.

Referring to FIG. 10 , the semiconductor device 10 may be disposed on afirst lead frame 5 a and may be connected to a second lead frame 5 busing a wire 20. In this case, the second lead frame 5 b may be disposedto surround a side surface of the first lead frame.

FIGS. 11A to 11E are sequence diagrams for describing a method ofmanufacturing a semiconductor device according to one embodiment.

The method of manufacturing a semiconductor device according to theembodiment may include growing a semiconductor structure 120, forming arecess 128, disposing a first electrode 142 and a second electrode 146,disposing a first insulating layer 131, a second reflective layer 145,and a second conductive layer 150, disposing a second insulating layer132, disposing a second conductive layer 150, disposing a bonding layer160, disposing a first conductive layer 165, and disposing passivationand an electrode pad 166.

First, referring to FIG. 11A, the semiconductor structure 120 may begrown. The semiconductor structure 120 may be grown on a first temporarysubstrate T. For example, a first conductive type semiconductor layer121, an active layer 122, and a second conductive type semiconductorlayer 123 may be grown on the first temporary substrate T.

The first temporary substrate T may be a growth substrate 170. Forexample, the first temporary substrate T may be made of at least oneselected from among sapphire (Al2O3), SiC, GaAs, GaN, ZnO, Si, GaP, InP,and Ge, but the present invention is not limited to such a material.

Further, the semiconductor structure 120 may be formed using, forexample, a metal-organic chemical vapor deposition (MOCVD) method, achemical vapor deposition (CVD) method, a plasma-enhanced chemical vapordeposition (PECVD) method, a molecular beam epitaxy (MBE) method, ahydride vapor phase epitaxy (HVPE) method, or the like, but the presentinvention is not limited thereto.

Descriptions of the first conductive type semiconductor layer 121, theactive layer 122, and the second conductive type semiconductor layer 123may be the same as described above. That is, the second conductive typesemiconductor layer 127 may include a first sub-layer 127 a and a secondsub-layer 127 b.

Referring to FIG. 11B, the semiconductor device may include the recess128. The recess 128 may be positioned to pass through the secondconductive type semiconductor layer 123 and the active layer 122 suchthat a partial region of the first conductive type semiconductor layer121 is exposed. For example, the recess 128 may include an outer sidesurface of the second conductive type semiconductor layer 123, an outerside surface of the active layer 122, and an exposed bottom surface ofthe first conductive type semiconductor layer 121.

Specifically, when a process margin for removing only the secondconductive type semiconductor layer 123 and the active layer 122 ispossible, the recess 128 may be composed of the outer side surface ofthe second conductive type semiconductor layer 123, the outer sidesurface of the active layer 122, and the bottom surface of the firstconductive type semiconductor layer 121. That is, the bottom surface ofthe first conductive type semiconductor layer 121 may be a surface thatis in contact with a top surface of the active layer 122.

However, when a process margin for disposing the recess 128 is takeninto account, the recess 128 may further include not only the exposedbottom surface of the first conductive type semiconductor layer 121 butalso an inclined surface of the first conductive type semiconductorlayer 121.

Referring to FIG. 11C, the first electrode 142 and the second electrode146 may be disposed on the semiconductor structure 120.

The first electrode 142 may be disposed in the recess 128 to be incontact with the exposed first conductive type semiconductor layer 124.In addition, the second electrode 146 may be disposed on the firstsub-layer 127 a of the second conductive type semiconductor layer 127.Here, the first electrode 142 and the second electrode 146 may bedisposed regardless of the order.

Referring to FIG. 11D, partial regions of the second electrode 146 andthe first sub-layer 127 a may be etched. Accordingly, a structure inwhich the first sub-layer 127 a and the second electrode 146 are stackedon the second sub-layer 127 b may be formed. In addition, a reflectivelayer 147 may be disposed on the second electrode 146 and the secondsub-layer 127 b. That is, the reflective layer 147 may be disposed on atop surface of the second sub-layer 147 b, a side surface of the firstsub-layer 147 a, and on a top surface of the second electrode 146 so asto surround the first sub-layer 147 a and the second electrode 146. As aresult, the reflective layer 147 reflects light received through thesecond sub-layer 147 b to improve optical characteristics and alsocauses the area of the first sub-layer 147 a to be reduced to improveelectrical properties due to a decrease in ohmic resistance.

Referring to FIG. 11E, a first insulating layer 131 may be disposed onthe reflective layer 147 and the semiconductor structure 120. Inaddition, the first insulating layer 131 may be partially removed byetching, and due to the etching, the reflective layer 147 may have apartially exposed surface.

Referring to FIG. 11F, the second conductive layer 150 may be disposedon the exposed surface of the reflective layer 147 such that thereflective layer 147 may be electrically connected to the secondconductive layer 150. In addition, since the second conductive layer 150is disposed on the first insulating layer 131, the second conductivelayer 150 may be electrically insulated from the first conductive typesemiconductor layer 121 by the first insulating layer 131. In addition,the second conductive layer 150 may be electrically connected to thesecond electrode 146 to form an electrical channel therebetween and maybe etched so as not to be exposed to an outer side surface of thesemiconductor device.

Referring to FIG. 11G, the second insulating layer 132 may be disposedon the semiconductor structure 120. The second insulating layer 132 maybe positioned on the second conductive layer 150, the first insulatinglayer 131, the second electrode 146, and the first electrode 142 and maybe disposed to surround the second conductive layer 150, the firstinsulating layer 131, the second electrode 146, and the first electrode142. In addition, the second insulating layer 132 may be disposed on thefirst insulating layer 131. Thus, even when cracks are generated in thefirst insulating layer 131, the second insulating layer 132 maysecondarily protect the semiconductor structure 120. The secondinsulating layer 132 may be disposed to expose a portion of a topsurface of the first electrode 142. For example, the second insulatinglayer 132 may pass through a portion of the top surface of the firstelectrode 142. The second insulating layer 132 may electrically insulatethe second electrode 146 from the first conductive layer 165.

Referring to FIG. 11H, the first conductive layer 165 may be disposed onthe exposed top surface of the first electrode 142. As a result, thefirst conductive layer 165 may be electrically connected to the firstreflective layer 147 so that the first conductive layer 165, the firstelectrode 142, and the first reflective layer 147 may have an electricalchannel. In addition, a first bonding layer 160 a may be disposed on thefirst conductive layer 165.

Referring to FIGS. 11I and 11J, the first bonding layer (not shown) maybe disposed on the first conductive layer 165, and a second bondinglayer (not shown) may be disposed below the substrate 170. In addition,the first bonding layer (not shown) and the second bonding layer (notshown) may be combined with each other to provide the bonding layerdescribed above. Here, the first bonding layer and the second bondinglayer may be combined under a predetermined temperature and pressure.

Further, the bonding layer 160 may include a conductive material. As anexample, the bonding layer 160 may include a material selected from thegroup consisting of gold, tin, indium, aluminum, silicon, silver,nickel, and copper, or an alloy thereof.

Further, the substrate 170 may be disposed on the second bonding layer(not shown). The bonding layer 160 may be formed by combining the firstbonding layer and the second bonding layer in the state in which thesubstrate 170 is disposed on the second bonding layer. However, thepresent invention is not limited thereto.

In addition, as described with reference to FIG. 1 , the substrate 170may be made of a conductive material. As an example, the substrate 170may include a metal or a semiconductor material. The substrate 170 mayinclude a metal having high electrical conductivity and/or thermalconductivity. In this case, heat generated when the semiconductor device10 operates may be rapidly discharged to the outside. In addition, whenthe substrate 170 is made of a conductive material, the first electrode142 may be supplied with a current from the outside through thesubstrate 170.

The substrate 170 may include a material selected from the groupconsisting of silicon, molybdenum, tungsten, copper, and aluminum or analloy thereof.

In addition, referring to FIG. 11K, the first temporary substrate T maybe separated from the semiconductor structure 120. For example, thefirst temporary substrate T may be separated from the semiconductorstructure 120 by emitting laser light onto the first temporary substrateT. However, the present invention is not limited to such a manner.

Referring to FIG. 11L, patterns may be present by etching the firstconductive type semiconductor layer 121 in some regions of thesemiconductor structure 120. In addition, the first insulating layer 131may be etched such that the second conductive layer 150 is exposed inthe etched region. In addition, the electrode pad 166 may be disposed ina hole.

Further, the passivation layer 180 may be disposed on top and sidesurfaces of the semiconductor structure 120. As described above, thepassivation layer 180 may have a thickness of 200 nm to 500 nm. When thethickness is greater than or equal to 200 nm, a device may be protectedfrom external moisture or foreign substances, thereby improvingelectrical and optical reliability of the device. When the thickness isless than or equal to 500 nm, it is possible to reduce stress applied tothe semiconductor device 10, to prevent a decrease in optical andelectrical reliability of the semiconductor device 10, and to reducecosts of the semiconductor device 10, which are increased by an increasein a processing time of the semiconductor device 10. However, thepresent invention is not limited to such a configuration.

Further, before the passivation layer 180 is disposed, uneven portionsmay be formed on the top surface of the semiconductor structure 120. Theuneven portions enable extraction efficiency of light emitted from thesemiconductor structure 120 to be improved. Heights of the unevenportions may be differently adjusted according to a wavelength of lightgenerated in the semiconductor structure 120.

In addition, as described above with reference to FIG. 9 , thesemiconductor structure may be disposed on the lead frame of the packageof the semiconductor device, or a circuit pattern of a circuit board.The semiconductor device may be applied to various types of light sourcedevices. As an example, the light source devices may be conceptsincluding a sterilizing device, a curing device, a lighting device, adisplay device, a vehicle lamp, and the like. That is, the semiconductordevice may be disposed in a case and applied to various electronicdevices configured to provide light.

The sterilizing device may include the semiconductor device according tothe embodiment to sterilize a desired region. The sterilizing device maybe applied to household appliances such as a water purifier, an airconditioner, and a refrigerator, but the present invention is notnecessarily limited thereto. That is, the sterilizing device may beapplied to all of various products (e.g., medical instruments) that needto be sterilized.

As an example, the water purifier may include a sterilizing deviceaccording to the embodiment to sterilize circulating water. Thesterilizing device may be disposed at a nozzle or a discharge portthrough which water circulates so as to irradiate water with ultravioletlight. Here, the sterilizing device may include a waterproof structure.

The curing device may include the semiconductor device according to theembodiment to cure various types of liquid. A liquid may be the broadestconcept including various materials which are cured when irradiated withultraviolet light. As an example, the curing device may cure varioustypes of resins. Alternatively, the curing device may be applied to curea cosmetic product such as a manicure.

The lighting device may include a light source module including thesubstrate and the semiconductor device according to the embodiment, aheat dissipation part configured to radiate heat of the light sourcemodule, and a power supply configured to process or convert anelectrical signal received from the outside and supply the signal to thelight source module. In addition, the lighting device may include alamp, a head lamp, a street light, or the like.

The display device may include a bottom cover, a reflective plate, alight-emitting module, a light guide plate, an optical sheet, a displaypanel, an image signal output circuit, and a color filter. The bottomcover, the reflective plate, the light-emitting module, the light guideplate, and the optical sheet may constitute a backlight unit.

The reflective plate may be placed on the bottom cover, and thelight-emitting module may emit light. The light guide plate may beplaced in front of the reflective plate to guide light emitted by thelight-emitting module forward, and the optical sheet may include a prismsheet or the like and may be placed in front of the light guide plate.The display panel may be placed in front of the optical sheet, the imagesignal output circuit may supply an image signal to the display panel,and the color filter may be placed in front of the display panel.

When the semiconductor device is used as a backlight unit of a displaydevice, the semiconductor device may be used as an edge-type backlightunit or a direct-type backlight unit.

The semiconductor device may be a laser diode in addition to theabove-described light-emitting diode.

Like the light-emitting device, the laser diode may include a firstconductive type semiconductor layer, an active layer, and a secondconductive type semiconductor layer that have the above-describedstructures. In addition, the laser diode may utilize anelectroluminescence phenomenon in which light is emitted when currentflows after bonding a p-type first conductive type semiconductor and ann-type second conductive type semiconductor but has a difference in thedirectionality and phase of the emitted light. That is, the laser diodeuses stimulated emission and constructive interference phenomena so thatlight having a specific single wavelength (monochromatic beam) may beemitted at the same phase and in the same direction. Due to thesecharacteristics, the laser diode may be used for optical communicationor medical equipment, semiconductor processing equipment, or the like.

A light-receiving device may include, for example, a photodetector,which is a kind of transducer configured to detect light and convert theintensity of the light into an electric signal. Such a photodetectorincludes a photocell (silicon or selenium), a photoconductor element(cadmium sulfide or cadmium selenide), a photodiode (PD) (for example, aPD having a peak wavelength in a visible blind spectral region or a trueblind spectral region), a phototransistor, a photomultiplier tube, aphototube (vacuum or gas-filled), an infra-red (IR) detector, and thelike, but the embodiment is not limited thereto.

In addition, the semiconductor device such as the photodetector maygenerally be manufactured using a direct bandgap semiconductor having ahigh photoconversion efficiency. Alternatively, the photodetector hasvarious structures and the most common structure may include a pin-typephotodetector using a p-n junction, a Schottky-type photodetector usinga Schottky junction, a metal-semiconductor-metal (MSM)-typephotodetector, or the like.

Like the light-emitting device, the photodiode may include a firstconductive type semiconductor layer, an active layer, and a secondconductive type semiconductor layer that have the above-describedstructures and may be formed as a p-n junction or a pin structure. Thephotodiode operates when a reverse bias or a zero bias is applied, andwhen light is incident on the photodiode, electrons and holes aregenerated such that current flows. In this case, the magnitude ofcurrent may be approximately proportional to the intensity of lightincident on the photodiode.

A photocell or solar cell, which is a kind of photodiode, may convertlight into current. Like the light-emitting device, the solar cell mayinclude a first conductive type semiconductor layer, an active layer,and a second conductive type semiconductor layer that have theabove-described structures.

Further, the solar cell may be used as a rectifier of an electroniccircuit through the rectification characteristics of a general diodeusing a p-n junction and may be applied to an ultra-high frequencycircuit and then may be applied to an oscillation circuit or the like.

Further, the above-described semiconductor device is not necessarilyimplemented only with semiconductors, and may further include a metalmaterial in some cases. For example, the semiconductor device such as alight-receiving device may be implemented using at least one of Ag, Al,Au, In, Ga, N, Zn, Se, P, and As and may be implemented using anintrinsic semiconductor material or a semiconductor material doped witha p-type dopant or an n-type dopant.

While the embodiments have been mainly described, they are only examplesand do not limit the present invention, and it may be known to thoseskilled in the art that various modifications and applications, whichhave not been described above, may be made without departing from theessential properties of the embodiments. For example, the specificcomponents described in the embodiments may be implemented while beingmodified. In addition, it will be interpreted that differences relatedto the modifications and applications fall within the scope of thepresent invention defined by the appended claims.

The invention claimed is:
 1. A semiconductor device comprising: asemiconductor structure including a first conductive type semiconductorlayer, a second conductive type semiconductor layer, and an active layerdisposed between the first conductive type semiconductor layer and thesecond conductive type semiconductor layer; a first electrodeelectrically connected to the first conductive type semiconductor layer;a second electrode electrically connected to the second conductive typesemiconductor layer; and a reflective layer disposed below the secondelectrode, wherein the second conductive type semiconductor layerincludes a first sub-layer and a second sub-layer that is disposedbetween the first sub-layer and the active layer and has an aluminum(Al) composition higher than an Al composition of the first sub-layer,the reflective layer is in contact with a bottom surface of the secondsub-layer, and the second electrode is in contact with the firstsub-layer, wherein a ratio of an area of the first sub-layer and an areaof the second sub-layer is in a range of 1:1.01 to 1:1.5, a ratio of anarea of the first electrode and an area of the second electrode is in arange of 1:3.88 to 1:5.8, and a ratio of an area of the reflective layerand the area of the second electrode is in a range of 1:2.4 to 1:3.6. 2.The semiconductor device of claim 1, wherein the Al composition of thefirst sub-layer is linearly reduced or stepwise reduced in a directionaway from the active layer.
 3. The semiconductor device of claim 2,wherein each of the first sub-layer and the second sub-layer includesaluminum (Al) and gallium (Ga), and in a system containing Al and Ga,the Al composition of the first sub-layer is in a range of 30% to 50%,and the Al composition of the second sub-layer is in a range of 50% to80%.
 4. The semiconductor device of claim 3, wherein the Al compositionof each of the first sub-layer and the second sub-layer increases in adirection toward the first conductive type semiconductor layer from thesecond electrode.
 5. The semiconductor device of claim 2, wherein aratio of the Al composition of the second sub-layer and the Alcomposition of the first sub-layer is in a range of 1:0.375 to 1:1. 6.The semiconductor device of claim 2, wherein the semiconductor structurefurther includes a recess disposed to a partial region of the firstconductive type semiconductor layer through the second conductive typesemiconductor layer and the active layer, the first electrode isdisposed in the recess, and the reflective layer and the secondelectrode are disposed to surround the recess.
 7. The semiconductordevice of claim 1, wherein the first sub-layer is disposed on a portionof the bottom surface of the second sub-layer, a side surface of thefirst sub-layer is in contact with the bottom surface of the secondsub-layer, the second electrode is disposed below the first sub-layer,and the reflective layer is disposed to be in contact with a sidesurface and a bottom surface of the second electrode.
 8. Thesemiconductor device of claim 1, further comprising: a first insulatinglayer disposed below the semiconductor structure and the reflectivelayer; a first conductive layer electrically connected to the firstelectrode; a second conductive layer disposed above the first conductivelayer and electrically connected to the reflective layer; a secondinsulating layer disposed between the first conductive layer and thesecond conductive layer; a bonding layer disposed below the secondconductive layer; and a substrate disposed below the bonding layer. 9.The semiconductor device of claim 1, wherein the reflective layerextends toward the bottom surface of the second sub-layer from a bottomsurface of the first sub-layer.
 10. The semiconductor device of claim 1,wherein the reflective layer is in contact with a side surface of thefirst sub-layer and surrounds the first sub-layer.